This invention relates to solar heating apparatus and, more particularly, to novel and highly effective solar heating apparatus which is especially adapted for water heating, which is more reliable than apparatus previously available, and which minimizes the amount of electrical or other energy consumed in comparison to the solar energy collected.
Because of the finite and dwindling supply of fossil fuels which have been man's most important source of energy for heating, transportation, etc., the quest for alternative energy sources has been intensive, especially during recent years. There are serious problems associated with the various actual and theoretical alternatives to fossil fuels. For example, atomic energy is considered by many to be too dangerous; energy from geothermal sources and from wind, waterfalls and tidal movements is reliably and economically available only in certain area; and energy from movements of the earth's crust cannot be harnessed by present technology.
Solar energy is widely recognized as in many ways an ideal substitute for fossil fuels, especially for certain applications such as water heating. It does not pollute the environment; it is continuously renewable; and the energy itself (as opposed to the equipment required to harness it) is free. The problems associated with the harnessing of solar energy are, however, considerable. First, while the total amount of solar energy received by the earth is immense, at any given time it is spread out over half the earth's surface and is everywhere of low intensity compared, for examply, to conditions inside an internal combustion engine, a steam boiler, or an atomic reactor. For this reason, a rather large capital outlay is necessary to harness significant amounts of solar energy. Second, solar energy is available only half the time at any point on the earth's surface, or even less to the extent that clouds, mountains, buildings, etc., block the sun's rays. Third, even when the sun's rays are not totally blocked, they are often considerably attenuated by pollution or, as shortly after sunrise, shortly before sunset, and during winter, by passing through a great thickness of atmosphere.
A copending applicationn of Zebuhr, Ser. No. 248,991, filed Mar. 30, 1981, now abandoned, discloses improved solar heating apparatus particularly adapted for heating water. However, some serious problems associated with the harnessing of solar energy to heat water that have not been fully solved even by the most advanced prior apparatus include water damage to certain parts of the apparatus and shock hazard to personnel in case of a leak and inefficient circulation of the water.